1. Field of the Invention
The invention concerns a method for determining and monitoring the ageing of blood bags in blood transfusion centers and health-care institutions.
2. Discussion of Background Information
At the present time, blood bags are collected in blood transfusion centers; each bag is dated at the time the blood is collected, which indicates the beginning of the life-span of the bag and the by-products, life-span that lasts a predetermined length of time; blood collected in bags is subjected to filtering, centrifugation and separation, which leads notably to production of a by-product which is a bag of red cells intended for transfusion whose life-span is forty five days beginning at the date on which the blood was collected; the bags of red blood corpuscles are stored in blood transfusion centers and delivered according to the requirements of health-care institutions. It sometimes occurs that bags of red blood corpuscles, which had been prepared as precautionary measures for an operation are not used; as it is impossible at present to have a firm guarantee of the quality of the contents of the bag of red blood corpuscles, with a view of them being re-used, the bag is destroyed. As destruction of unused bags of red blood corpuscles represents at present a loss of twelve percent of the blood bags collected, it is essential to reduce this wastefulness.
As the bags of red blood corpuscles are at present transported between the blood transfusion centre and the health-care institution without any special precautions, a study is under way with a transport company for guaranteeing the continuity of the cold chain between these two establishments; in this case, the blood bag is placed in a refrigerated container inside which a device is placed indicating the temperature in the container throughout transport; as the bags of red blood corpuscles are placed in an appropriate refrigerator on arrival at the health-care institution, these bags can be returned to the blood transfusion centre if they have not been removed from the refrigerator in the mean time, to be placed at the disposal of a surgeon.
When the blood is collected, it is transferred into a main blood bag connected to a filter, itself connected to a primary blood bag; the primary blood bag is part of a group of bags that also include three secondary bags to which it is connected by flexible tubing arranged in parallel; the blood from the main blood bag is filtered and introduced into the primary blood bag; the primary blood bag is centrifuged in order to separate the red cells, platelets and serum which are then respectively transferred into each of the three bags and the bag containing the red cells is the one used to carry out blood transfusions. As a reminder, platelets are isolated only when there is a specific supply requirement—otherwise they remain with the red cells and only two secondary bags are used.
A traceability device for blood bags, as per patent application FR-9804802 is under development; it integrates a silicon chip with the blood bag; each silicon chip is fitted with a loop antenna which communicates with the loop antenna on an electronic communication device, connected to a computer, capable of supplying the silicon chip on the one hand with energy and on the other with data which it stores in memory and which it is capable of restoring to the said computer through the electronic communication device; a mother silicon chip is attached to the mother blood bag which receives all the data concerning the donor and the results of analyses that have enabled the mother blood bag to be qualified; the electronic mother chip is fixed on a rectangular-shaped flexible chip support several centimeters long, on which a metallized loop circuit is printed that forms the communications loop antenna; in a preferred version of the invention, the flexible chip support for the primary silicon chip is placed on one of the largest surfaces of the mother blood bag beneath a rectangular label covering the major part of one of the principal surfaces; preferably the mother chip support is always put in the same place in relation to the label for facilitating positioning of the antenna on the electronic communication device. A patent application FR-9908887 describes a weighing and stirring device fitted with an electronic communication device which enables the blood donor's particulars and blood collection conditions to be recorded in the electronic mother chip on the mother blood bag; the blood in the mother blood bag is transferred through a filtration unit into the primary blood bag; the primary blood bag comprises a primary silicon chip to which the data contained in the electronic mother chip is transferred together with information on filtration conditions; the primary blood bag is then centrifuged; the constituents are separated and are introduced into the secondary blood bags; secondary blood bags are equipped with secondary silicon chips, identical to the mother and primary silicon chips, which are fixed to a flexible chip support placed under a label covering one side of the secondary blood bag, preferably in such a position that, when the mother, primary and secondary blood bags are placed above each other, the mother and primary silicon chip supports do not cover each other or the secondary flexible chip supports; information is entered into the secondary silicon chips on the secondary bags, in other words the red cell bag, the serum bag and possibly the platelet bag, by transferring data from the primary silicon chip on the primary blood bag, and completing it with data concerning the parameters used for separating the blood constituents. Concerning any red cell bag that has been used for a blood transfusion, at the end of the bag's use, the secondary silicon chip integrated into it contains information concerning its conditions of use and notably the identity of the patient who has received the transfusion.